When television signals having an oblong aspect ratio, particularly those signals for wide screen televisions and having an aspect ratio of 9:16, are broadcast and received by means of television receivers for such exclusive use, realistic and exciting pictures can be obtained. However, when such signals are received by means of conventional type television receivers which are normally adapted to receive television signals having an aspect ratio of 3:4, the picture is not received or displayed upon the right and left ends of the screen (or is received or displayed upon only either the right end or the left end if the signals are received) so as not to have no-picture or black band portions or sectors upon the upper and lower portions of the screen as shown in FIG. 7(b). These ends portions are called "side panels". FIG. 7(a) illustrates the case where the picture is received and displayed upon the entire area of the wide screen television so as to extend between the left and right sides of a conventional type television set, yet there also exists or is developed no-picture sectors or regions within the upper and lower portions of the screen. This state is called the "letter box type picture or display". Because the signals for a wide screen television set or monitor cannot be completely or properly received upon a conventional type television set, another type of television system is provided, which is in effect, a compromise between the aforenoted two different types of systems or display modes and which can in fact be normally received by wide means of a wide screen television set or monitor.
In the case illustrated within FIG. 7C, side panels exist to some extent, and upper and lower no-picture or black band regions or sectors are also present but the same extend to relatively short distances. However, in order to receive wide screen television pictures upon a television set or monitor which is especially designed for such exclusive use, it is necessary to transmit television picture signals having such side panels by some means and to subsequently process and display these signals within such television set or monitor.
In order to attain such an objective, it has been proposed to divide the frequency band for the side panel signals into low and high bands and to broadcast the picture signals by means of multiplexing them by separate methods. Based upon such a concept, a system is not under experimental study at the David Sarnoff Institute in the United States. By means of this system, high frequency components are diffused throughout the entire picture to be broadcast through means of frequency multiplexing, and low frequency components are compressed and inserted into the left and right ends of the raster. When these signals re received by means of a television receiver especially designed for such exclusive use, the high frequency and low frequency components synthesized and displayed upon the wide screen television monitor. When these signals are received upon a normal or conventional television receiver, the picture is displayed with the side panels partially omitted.
When the signals for the side panels are divided into the two frequency bands of the high and low frequencies, a high-pass filter and a low-pass filter are used, but it is impossible to obtain ideal cut-off frequency characteristics. Therefore, it is unavoidable to develop overlapped regions in connection with the filter characteristics near the cut-off frequency, and such band, such as, for example, 0.5 MHz, cannot be neglected when the above signals rae set by means of multiplex transmission. The high frequency components of the side panels, generated by means of such filters, have a wide band and cannot be received within the no-picture or block band sectors within the upper and lower portions of the screen. Unavoidably, these signals are therefore diffused over the entire screen of the television set or monitor as a result of being multiplexed at the David Sarnoff Institute. Accordingly, interference occurs upon the screen and the picture quality is deteriorated in this system because the high frequency components of the side panels, originally irrelevant, are multiplexed upon the screen.